1. Field of the Invention
This invention relates to a method of controlling a centralized or duct-type air conditioning system including a single indoor unit for supplying the controlled air through duct to a plurality of rooms in a building.
2. Description of the Prior Art
Various centralized or duct-type air conditioning systems are known in which the conditioned air is supplied from a single indoor unit through ducts to individual rooms to keep the temperature and humidity in the rooms at comfort values. In one such known system disclosed in Japanese Patent Laid-open Publication No. 61-91425, there are provided two ducts one of which is used for the passage of the cool air to be supplied to the respective rooms, the other duct being used for the passage of the recirculated air returning from the rooms. Alternately, in the heating mode, the last-mentioned duct is used for the passage of the warm air to be blown off into the rooms while the first-mentioned duct is used for the passage of the recirculated air returning from the rooms. The capacity of the disclosed air conditioning system is controlled by control shutters or dampers which are disposed at supply air grilles of the respective rooms and which are manually or electrically moved between a fully opened position and a fully closed position through a half-closed position.
The prior duct-type air conditioning system has no capacity controller other than the aforesaid control dampers. Consequently, since a fan is driven at a constant speed, as the number of empty room (i.e. closed damper) increases, so the internal pressure of the duct increases which will increase the amount of supply air per unit time. Thus, the regulation of air conditioning capacity for one room affects the air conditioning capacity for another room with the result that a stable air conditioning is difficult to obtain. The foregoing drawback may be overcome by releasing part of the internal pressure to another duct, thereby maintaining the duct internal pressure in a controlled condition against undue elevation. Such attempt however result in a waste in the capacity of the fan. Heretofore, a satisfactory method of controlling the centralized or duct-type air conditioning system has not been proposed.